Cleaning sheets comprising a fibrous web of carded staple fibers hydroentangled with a reinforcing fibrous web

ABSTRACT

A cleaning sheet for removing particulate matter from a surface comprises a substrate comprising a first fibrous web comprising carded staple fibers and a reinforcing fibrous web comprising fibers selected from the group consisting of thermal bonded fibers, meltblown fibers, hydroentangled fibers, and spunbonded fibers. The first fibrous web is hydroentangled with the reinforcing fibrous web to form the substrate. The resulting cleaning sheet has a CD elongation of less than about 100% at a load of 500 grams. The cleaning sheet is preferably free of a scrim material and can further comprise an optional additive material. A method of removing particulate matter from a surface comprises contacting the surface with a cleaning sheet of the present invention.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.10/174,895, filed Jun. 19, 2002 (Attorney Docket No. 8620), which claimsthe benefit of U.S. Provisional Application Ser. No. 60/302,332, filedJun. 29, 2001 (Attorney Docket No. 8620P).

TECHNICAL FIELD

The present invention relates to cleaning sheets particularly suitablefor removal and entrapment of dust, lint, hair, sand, food crumbs, grassand the like.

BACKGROUND OF THE INVENTION

The use of nonwoven sheets for dry dust-type cleaning is known in theart. Such sheets typically utilize a composite of fibers wherein thefibers are bonded together via adhesive, thermal bonding, entangling orother forces. See, for example, U.S. Pat. No. 3,629,047 and U.S. Pat.No. 5,144,729. To provide a durable wiping sheet, reinforcement meanshave been combined with staple fibers in the form of a continuousfilament or network structure. See, for example, U.S. Pat. No.4,808,467, U.S. Pat. No. 3,494,821 and U.S. Pat. No. 4,144,370. Also, toprovide a product capable of withstanding the rigors of a wipingprocess, prior nonwoven sheets have employed strongly bonded fibers viaone or more of the forces mentioned above. While durable materials areobtained, such strong bonding may adversely impact the materials'ability to pick up and retain particulate dirt.

In an effort to address this concern, U.S. Pat. No. 5,525,397 issuedJun. 11, 1996 to Shizuno et al., describes a cleaning sheet comprising apolymeric network layer (i.e. scrim material) and at least one nonwovenfiber layer, wherein the two layers are lightly hydroentangled so as toprovide a sheet having a specifc low entanglement coefficient,elongation, and breaking strength. The resulting sheet is said toprovide strength and durability, as well as improved dust collectingperformance because the composite fibers are lightly hydroentangled.While the sheets described in the '397 patent are alleged to addresssome of the problems with prior nonwoven cleaning sheets, those sheetsappear to consist of fibers having a generally uniform denier and thesheets made of such fibers appear to be generally of a uniform basisweight, at least on a macroscopic level; and are essentially of auniform caliper, again on a macroscopic level. The result of a sheetmade of fibers having a uniform denier and having a uniform basis weightis that the material is not particularly suitable for collecting andentrapping soil of a diverse size, shape, etc.

To improve the suitability of cleaning sheets to collect and entrap soilof diverse size, PCT Application WO 98/52458, assigned to The Procter &Gamble Co., teaches that by providing increased three-dimensionality, inthe macroscopic sense, to cleaning sheets, enhanced soil removal isachieved. This three-dimensionality can be achieved by the use ofmaterials which provide contractile forces within the body of the sheet.These contractile forces can cause the layer or layers of the sheet tofold into relatively random peaks and valleys. These peaks and valleysprovide a diverse set of collection surfaces within the sheet. Itappears that the cleaning sheets are comprised of fibers having agenerally uniform denier, particularly a denier of less than about 4.0.The sheets can include a polymeric net, or scrim material, to enhancethe integrity of the resulting cleaning sheets.

Although polymeric nets or scrim materials can be useful in cleaningsheets to provide caliper, strength and integrity, polymeric netting orscrim materials tend to be rather difficult to process, and thus it canbe troublesome to manufacture cleaning sheets comprising such polymericnets or scrim materials. It has thus been desired to provide an improvedcleaning sheet with sufficient caliper, integrity and strength having aneffective ability to remove particulate matter from a surface, withoutthe need to incorporate a polymeric netting or scrim material into thecleaning sheet.

Accordingly, it is an object of the present invention to provide animproved cleaning sheet that effectively removes and retains particulatematerial from surfaces, while being thick enough and strong enough towithstand the rigors of a typical household cleaning process, evenwithout the incorporation of a polymeric net or scrim material in thestructure of the cleaning sheet.

SUMMARY OF THE INVENTION

The present invention relates to a cleaning sheet for removingparticulate matter, such as dust or dirt, from a surface, the cleaningsheet comprising a substrate comprising a first fibrous web comprisingcarded staple fibers and a reinforcing fibrous web comprising fibersselected from the group consisting of thermal bonded fibers, meltblownfibers, hydroentangled fibers, and spunbonded fibers. The first fibrousweb is hydroentangled with the reinforcing fibrous web to form thesubstrate. The resulting cleaning sheet has a CD elongation of less thanabout 100%, preferably less than about 70%, and more preferably lessthan about 50%, at a load of 500 grams. The reinforcing fibrous webprovides the cleaning sheet with sufficient strength and integrity toeffectively removing particulate matter from surfaces. The resultingcleaning sheet is therefore sufficiently strong and has sufficientintegrity for cleaning household surfaces therewith, even when thecleaning sheet is free of a scrim material.

In a preferred embodiment, the substrate comprises first fibers andsecond fibers, wherein said first fibers and said second fibers havedifferent denier, and wherein said cleaning sheet has a caliper of fromabout 0.3 to about 3 mm, preferably at least about 1 mm. In general, thefirst fibers will have a denier of from about 0.5 to about 15 and thesecond fibers have a denier of from about 0.5 to about 15, wherein thedifference between the denier of the first fibers and the denier of thesecond fibers is at least about 0.5. Caliper of the cleaning sheet canbe important, for both cleaning performance and aesthetics. The cleaningsheets of the present invention exhibit desirable caliper, even withoutthe inclusion of a scrim material. The combination of fibers havingrelatively high denier with fibers having relatively low denier canprovide the cleaning sheet with the desired caliper. As a result, thepresent cleaning sheets are thus preferably free of a scrim material.

The present invention further relates to a cleaning implement comprisinga handle and a mop head for attaching the present cleaning sheetsthereto.

The present invention further relates to methods of removing particulatematter from surfaces by contacting the surfaces with the cleaning sheetsof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

I. Definitions

As used herein, the term “comprising” means that the various components,ingredients, or steps, can be conjointly employed in practicing thepresent invention. Accordingly, the term “comprising” encompasses themore restrictive terms “consisting essentially of” and “consisting of”.

As used herein, the term “hydroentanglement” means generally a processfor making a material wherein a layer of loose fibrous material (e.g.,polyester) is supported on an apertured patterning member (e.g. formingbelt) and is subjected to water pressure differentials sufficientlygreat to cause the individual fibers to entangle mechanically to providea fabric. The apertured patterning member may be formed, e.g., from awoven screen, a perforated metal plate, etc.

As used herein, the term “Z-dimension” refers to the dimensionorthogonal to the length and width of the cleaning sheet of the presentinvention, or a component thereof. The Z-dimension usually correspondsto the thickness of the sheet.

As used herein, the term “X-Y dimension” refers to the plane orthogonalto the thickness of the cleaning sheet, or a component thereof. The Xand Y dimensions usually correspond to the length and width,respectively, of the sheet or a sheet component.

As used herein, the term “layer” refers to a member or component or webof a cleaning sheet whose primary dimension is X-Y, i.e., along itslength and width. It should be understood that the term layer is notnecessarily limited to single layers or sheets or webs of material. Thusthe layer can comprise laminates or combinations of several sheets orwebs of the requisite type of materials. Accordingly, the term “layer”includes the terms “layers” and “layered.”

For purposes of the present invention, an “upper” layer of a cleaningsheet is a layer that is relatively further away from the surface thatis to be cleaned (i.e., in the implement context, relatively closer tothe implement handle during use). The term “lower” layer converselymeans a layer of a cleaning sheet that is relatively closer to thesurface that is to be cleaned.

As used herein, the term “total aggregate basis weight” refers to theaverage basis weight of an entire cleaning sheet, when viewed as a wholesheet.

As used herein, the term “denier” refers to the number of unit weightsof 0.05 grams per 450 meter length of an individual continuous fiberfilament or an individual staple fiber if it were continuous.

As used herein, the term “caliper” refers to the thickness of a cleaningsheet of the present invention. Caliper can be measured using a Mitutoyocaliper gauge, which is slowly lowered onto the surface of the substrateof the cleaning sheet such that no excessive force is applied to thesubstrate.

As used herein, the term “CD Elongation” refers to the amount ofdeformation of the cleaning sheet in the cross direction caused by atensile force of 500 grams that is applied to a 30 mm wide sample of thecleaning sheet. CD elongation is calculated as a percentage of theoriginal sample length. The tensile force for measuring CD elongationcan be applied, and CD elongation measured, using a Sintech RenewInstron 7310 device with a 100 Newton or larger load cell.

All percentages, ratios and proportions used herein are by weight unlessotherwise specified. All references cited are incorporated herein byreference unless otherwise stated.

II. Cleaning Sheet

The present invention encompasses cleaning sheets comprising a substratecomprising a first fibrous web hydroentangled with a reinforcing fibrousweb to improve the strength and integrity of the cleaning sheet,especially when the cleaning sheet is free of a scrim material.Applicants have found that a cleaning sheet comprising a reinforcingfibrous web can have sufficient strength and integrity for removingparticulate matter from surfaces, even without the inclusion of a scrimmaterial in the cleaning sheet. CD elongation can be an important aspectof a cleaning sheet, especially for providing sufficient strength andintegrity for the cleaning sheet to be used for cleaning householdsurfaces, especially hardwood floors, ceramic tile, and furnituresurfaces. The present cleaning sheets are able to effectively remove andretain particulate material from surfaces.

The substrates of the present cleaning sheets are formed of a firstfibrous web (or layer) and a reinforcing fibrous web (or layer). Thefirst fibrous web herein comprises carded staple fibers; and thereinforcing fibrous web herein is preferably different in type (i.e.thermal bonded fibers, meltblown fibers, spunbonded fibers,hydroentangled fibers, and the like).

The substrate of the present cleaning sheets comprises a first fibrousweb (or layer) and a second reinforcing fibrous web (or layer). Areinforcing fibrous web is especially preferred wherein the firstfibrous layer comprises carded staple fibers, such as carded staplepolyester fibers. Carded staple fibers, while being particularlyeffective for removing particulate matter from surfaces, can result in acleaning sheet without sufficient strength and integrity. Thereinforcing fibrous web tends to provide enhanced strength and integrityto the resulting cleaning sheet, which is especially important whencleaning household surfaces such as hardwood floors, ceramic tile (withgrout), furniture surfaces, and the like. The reinforcing fibrous webtypically comprises fibers selected from the group consisting of thermalbonded fibers, meltblown fibers, spunbonded fibers, hydroentangledfibers, and mixtures thereof. The reinforcing fibrous web is preferablyfree of non-random perforations or open areas.

The reinforcing fibrous web herein will preferably have a denier of fromabout 0.5 to about 12, more preferably from about 1 to about 6, and evenmore preferably from about 2 to about 4.

In a preferred embodiment of the present invention, the substratecomprises at least three fibrous webs. A first fibrous web and a secondfibrous web both comprise carded staple fibers, and a third reinforcingfibrous web comprises spunbonded fibers or thermal bonded fibers. Thefirst and second fibrous webs are hydroentangled with the third fibrousweb to form the substrate, preferably with the third fibrous webpositioned in between the first and second fibrous webs.

The present substrates can further comprise four, five, six, or morefibrous webs (or layers).

The substrates of the cleaning sheets of the present invention typicallyhave a total aggregate basis weight of at least about 20 g/m²,preferably at least about 40 g/m², more preferably at least about 45g/m2, and even more preferably at least about 60 g/m². The totalaggregate basis weight of the present cleaning sheets is typically nogreater than about 200 g/m², preferably no greater than about 150 g/m²,and more preferably no greater than about 100 g/m², and even morepreferably no greater than about 80 g/m². Each fibrous web willtypically have a basis weight of from about 25 to about 100 g/m²,preferably from about 30 to about 75 g/m², and more preferably fromabout 40 to about 50 g/m².

In the preferred embodiments that comprise a first fibrous web and asecond reinforcing fibrous web, the reinforcing fibrous web willgenerally have a basis weight that is from about 5% to about 70%,preferably from about 10% to about 50%, and more preferably from about15% to about 30%, of the total aggregate basis weight of the substrateof the cleaning sheet. The specific basis weight of the reinforcinglayer will generally be from about 5 to about 30 g/m², and morepreferably from about 10 to about 20 g/m².

While a reinforcing fibrous web can be incorporated in the substrate ofthe present cleaning sheet to enhance the strength and integrity of thecleaning sheet, the reinforcing fibrous web can also affect theaesthetic feel of the cleaning sheet to a consumer. For example, areinforcing fibrous web that comprises spunbond polyester fibers tendsto make the cleaning sheet more stiff compared to a reinforcing fibrousweb that comprises spunbond polypropylene fibers, which makes thecleaning sheet feel softer to the touch. A cleaning sheet that does notcomprise a reinforcing fibrous web tends to feel even softer to thetouch, but has far less strength and integrity.

In order for the cleaning sheets to effectively clean surfaces, thecleaning sheets are sufficiently strong and not tear easily (e.g. sheetintegrity). As a result, the present cleaning sheets will have a CDelongation of no greater than about 100%, preferably no greater thanabout 70%, and more preferably no greater than about 50%. The cleaningsheets can, however, have a certain amount of CD elongation, especiallywhen the cleaning sheet is to be attached to a cleaning implement asdescribed hereinafter. In this respect, a certain amount of CDelongation can be desirable, so that a consumer of the cleaning sheetcan slightly stretch the cleaning sheet around the mop head of thecleaning implement and attach it to the mop head, especially when thecleaning sheet is attached to the cleaning implement via “grippers” onthe mop head. The present cleaning sheets will thus preferably have a CDelongation of at least about 10%, preferably at least about 12%, andmore preferably at least about 15%.

The desired CD elongation can be achieved even if the substrate of thepresent cleaning sheet does not comprise a scrim material. Scrimmaterial can, however, be used to provide enhanced strength andintegrity of the cleaning sheet. As used herein, the term “scrimmaterial” refers to a polymeric netting material or a network sheethaving non-random perforations therethrough, as described in U.S. Pat.No. 5,525,397, incorporated herein by reference. The present cleaningsheets are, however, preferably free of a scrim material, especiallywhen the cleaning sheet comprises a reinforcing fibrous web as describedherein.

The substrates of the present invention can be made of a variety offibers types. Fibers particularly suitable for forming the substrates ofthe present cleaning sheets include, for example, natural fibers, e.g.wood pulp, cotton, wool, and the like, as well as biodegradeable fibers,such as polylactic acid fibers, and synthetic fibers such as polyolefins(e.g., polyethylene and polypropylene), polyesters, polyamides,synthetic cellulosics (e.g., RAYON®, Lyocell), cellulose acetate,bicomponent fibers, and blends thereof. Preferred starting materials formaking the substrates of the cleaning sheets of the present inventionare synthetic materials, which can be in the form of carded, spunbonded,meltblown, airlaid, or other structures. Particularly preferred arepolyesters, especially carded polyester fibers. The degree ofhydrophobicity or hydrophilicity of the fibers is optimized dependingupon the desired goal of the sheet, either in terms of type of soil tobe removed, the type of additive material that is provided, when anadditive material is present, biodegradability, availability, andcombinations of such considerations. In general, the more biodegradablematerials are hydrophilic, but the more effective materials tend to behydrophobic.

The substrates of the cleaning sheets of the present invention can bemade using either a woven or nonwoven process, or by forming operationsusing materials laid down on forms, especially in belts, and/or byforming operations involving mechanical actions/modifications carriedout on films. The structures can be made by any number of methods (e.g.,spunbonded, meltblown, resin bonded, heat-bonded, air-through bonded,etc.), once the desired characteristics are known. However, thepreferred structures are nonwoven, and especially those formed byhydroentanglement, since they provide highly desirable open structures.Therefore, preferred cleaning sheets are hydroentangled, nonwovenstructures formed on belts and/or forming operations that include araised three-dimensional pattern as described hereinafter.

In a preferred embodiment, the substrates of the present cleaning sheetswill comprise first fibers and second fibers having different denier,the fibers typically having a denier of from about 0.5 to about 15denier, preferably from about 0.7 to about 12, and more preferably fromabout 1 to about 6. The difference in denier between the first fibersand second fibers of the substrates of the present cleaning sheets willgenerally be at least about 0.5, preferably at least about 0.7, and morepreferably at least about 1 denier. In a preferred embodiment, the firstfibers will have a denier of from about 0.5 to about 2 and the secondfibers will have a denier of from about 1 to about 6. Substratescomprising first and second fibers having different denier willtypically enhance the caliper of the cleaning sheet, which can beimportant for large particulate matter pick-up cleaning performance andenhancing the particulate capacity of the cleaning sheet.

The substrates of the present cleaning sheets will preferably comprise aratio of first fibers to second fibers of from about 100:1 to about1:100, more preferably from about 10:1 to about 1:20, and morepreferably from about 1:5 to about 1:10, by weight.

The caliper of the resulting cleaning sheets will be from about 0.3 toabout 3 mm, preferably from about 0.5 to about 2 mm, and more preferablyfrom about 1 to about 1.8 mm. The preferred cleaning sheets herein willhave a caliper of at least about 1 mm, preferably from about 1 to about2 mm.

Preferred Macroscopic Three-Dimensionality

The cleaning sheets can be relatively planar on a macroscopic level(such as those cleaning sheets disclosed in U.S. Pat. No. 5,525,397,incorporated herein by reference) or can have macroscopicthree-dimensionality (such as those cleaning sheets disclosed inco-pending U.S. application Ser. No. 09/082,396, filed May 20, 1998 byFereshtehkhou et al., incorporated herein by reference). Preferably, thecleaning sheets exhibit macroscopic three-dimensionality which resultsin a cleaning sheet have greater effectiveness for removing andretaining particulate matter from surfaces. The preferred cleaningsheets exhibiting macroscopic three-dimensionality have certaincharacteristics such as Average Peak-to-Peak Distance, Average HeightDifferential, and Surface Topography Index. Such characteristics aremeasured according to the methods described in detail in co-pending U.S.application Ser. No. 09/082,396, filed May 20, 1998 by Fereshtehkhou etal., incorporated herein by reference.

The preferred cleaning sheets having macroscopic three-dimensionalitywill exhibit one or more of the following characteristics:

-   -   (a) an Average Peak-to-Peak Distance of from about 1 to about 20        mm, preferably from about 3 to about 16 mm, and more preferably        from about 4 to about 12 mm;    -   (b) an Average Height Differential of from about 0.5 to about 6        mm, preferably from about 1 to about 3 mm, and more preferably        about 1.5; and/or    -   (c) a Surface Topography Index of from about 0.01 to about 10,        preferably from about 0.1 to about 5, more preferably from about        0.2 to about 3, still more preferably from about 0.3 to about 2.        These macroscopic three-dimensionality characteristics are        described in more detail in co-pending U.S. application Ser. No.        09/082,396, filed May 20, 1998 by Fereshtehkhou et al.

Optional Additive Material

The present cleaning sheets can further comprise an additive materialaffixed to the substrate. The use of a low level of additive material,uniformly attached on at least one, preferably continuous area of thesheet in an effective amount to improve the adherence of soil,especially particulates, and especially those particulates that provokean allergic reaction, provides a surprising level of control over soiladherence. At least in those areas where the additive is present on thesheet, the low level is important for such use, since, unliketraditional dusting operations where oils are applied as liquids, or assprays, there is much less danger of creating a visible stain,especially on such non-traditional surfaces, when the sheet is used.

The cleaning performance of any of the cleaning sheets of the presentinvention can be further enhanced by treating the fibers of the sheet,especially surface treating, with any of a variety of additives,including surfactants or lubricants, that enhance adherence of soils tothe sheet. When utilized, such additives are added to the non-aperturedcleaning sheet at a level sufficient to enhance the ability of the sheetto adhere soils. Such additives are preferably applied to the cleaningsheet at an add-on level of at least about 0.01%, more preferably atleast about 0.1%, more preferably at least about 0.5%, more preferablyat least about 1%, still more preferably at least about 3%, still morepreferably at least about 4%, by weight. Typically, the add-on level isfrom about 0.1 to about 25%, more preferably from about 0.5 to about20%, more preferably from about 1 to about 15%, still more preferablyfrom about 3 to about 10%, still more preferably from about 4 to about8%, and most preferably from about 4 to about 6%, by weight. Additivematerials can be selected from the group consisting of a wax, an oil,and mixtures thereof. A preferred additive is a wax or a mixture of anoil (e.g., mineral oil, petroleum jelly, etc.) and a wax. Suitable waxesinclude various types of hydrocarbons, as well as esters of certainfatty acids (e.g., saturated triglycerides) and fatty alcohols. They canbe derived from natural sources (i.e., animal, vegetable or mineral) orcan be synthesized. Mixtures of these various waxes can also be used.Some representative animal and vegetable waxes that can be used in thepresent invention include beeswax, carnauba, spermaceti, lanolin,shellac wax, candelilla, and the like. Representative waxes from mineralsources that can be used in the present invention includepetroleum-based waxes such as paraffin, petrolatum and microcrystallinewax, and fossil or earth waxes such as white ceresine wax, yellowceresine wax, white ozokerite wax, and the like. Representativesynthetic waxes that can be used in the present invention includeethylenic polymers such as polyethylene wax, chlorinated naphthalenessuch as “Halowax,” hydrocarbon type waxes made by Fischer-Tropschsynthesis, and the like.

When a mixture of mineral oil and wax is utilized, the components willpreferably be mixed in a ratio of oil to wax of from about 1:99 to about7:3, more preferably from about 1:99 to about 1:1, still more preferablyfrom about 1:99 to about 3:7, by weight. In a particularly preferredembodiments, the ratio of oil to wax is about 1:1 or about 3:7, byweight, and the additive is applied at an add-on level of about 5%, byweight. A preferred mixture is a 1:1 mixture of mineral oil and paraffinwax or a 3:7 mixture of mineral oil and paraffin wax.

Particularly enhanced cleaning performance is achieved when macroscopicthree-dimensionality and additive are provided in a single cleaningsheet. As discussed hereinbefore, these low levels are especiallydesirable when the additives are applied at an effective level andpreferably in a substantially uniform way to at least one discretecontinuous area of the sheet. Use of the preferred lower levels,especially of additives that improve adherence of soil to the sheet,provides surprisingly good cleaning, dust suppression in the air,preferred consumer impressions, especially tactile impressions, and, inaddition, the additive can provide a means for incorporating andattaching perfumes, pest control ingredients, antimicrobials, includingfungicides, and a host of other beneficial ingredients, especially thosethat are soluble, or dispersible, in the additive. These benefits are byway of example only. Low levels of additives are especially desirablewhere the additive can have adverse effects on the substrate, thepackaging, and/or the surfaces that are treated.

Other suitable additive materials herein include polymeric additives,especially those with specific adhesive characteristics such as specificTack Values, Adhesive Work Values, Cohesion/Adhesion Ratios, StringinessValues, T_(g) Values, and/or molecular weight. The polymeric additivematerial is selected in order to improve the pick-up of fine particulatematter such as dust, lint, and hair, and especially larger particulatematter typically found on household floors and surfaces such as crumbs,dirt, sand, hair, crushed food, grass clippings and mulch. In addition,the type and amount of the additive material is carefully selected inorder to improve particulate pick-up of the cleaning sheet, whilemaintaining the ability of the cleaning sheet to easily glide across thesurface being cleaned. If the cleaning sheet is too tacky as a result ofthe additives incorporated therein, the cleaning sheet will not easilyglide across the surface, leading to consumer dissatisfaction.

Preferred polymeric additives include, but are not limited to, thoseselected from the group consisting of pressure sensitive adhesives,tacky polymers, and mixtures thereof. Suitable pressure sensitiveadhesives comprise an adhesive polymer, which is optionally incombination with a tackifying resin, plasticizer, and/or other optionalcomponents. Suitable tacky polymers include, but are not limited to,polyisobutylene polymers, N-decylmethacrylate polymers, and mixturesthereof.

Preferred pressure sensitive adhesives can be selected for incorporationin the present cleaning sheets based on the adhesive characteristics ofthe pressure sensitive adhesive, including Adhesive Work Value, TackValue, Cohesive/Adhesive Ratio, and Stringiness Value. These adhesivecharacteristics, and methods for measuring such adhesivecharacteristics, have been described in detail in co-pending U.S.application Ser. No. 09/821,953 filed Mar. 30, 2001 by Kacher et al.,which is incorporated herein by reference. Preferred polymeric additivematerials are also described in detail in said co-pending application.

The substrate of the present invention is preferably free of materialsthat would diminish the ability of the cleaning sheet to generate anelectrostatic charge. An electrostatic charge enhances the ability ofthe cleaning sheet to remove and retain particulate matter from thesurface being cleaned. For example, cationic surfactants, such as fabricsoftening actives, can diminish the ability of a cleaning sheet togenerate electrostatic charge. The present cleaning sheets are thuspreferably free of cationic surfactants, such as fabric softeningactives.

Process for Manufacture

The present cleaning sheets can be formed of a variety of process asdiscussed hereinbefore. An especially preferred process for making acleaning sheet of the present invention comprises the step ofhydroentangling the fibers of the structure on a forming belt having adesired pattern of raised and recessed regions. Examples of such formingbelts are described in U.S. Pat. No. 5,275,700, which is incorporatedherein by reference. The forming belt can comprise machine-directionwarp yarns, cross-machine-direction weft yarns, and a pattern framework.The pattern framework may be formed on the warp and weft yarns by anymethod known in the art. See, e.g., U.S. Pat. No. 5,275,700. Theframework has solid areas and void areas which correspond to therecessed regions and the raised regions, respectively, of the cleaningsheet formed on the belt. The framework of the forming belt has athickness, and has solid and void areas such that the desired pattern ofraised regions will be formed on the cleaning sheet in thehydroentangling process. The framework can have a thickness ranging fromabout 0.07 mm to about 2.0 mm, preferably from about 0.2 mm to about 1.5mm, and more preferably from about 0.4 mm to about 0.9 mm. It should benoted that the X-Y dimensions of the raised regions are slightly greaterthan the width of the form void areas in the form belt. Without beinglimited by theory, it is believed that during the hydroentanglingprocess the fibers which are pushed into the voids are under compressiveforce. After hydroentagling, when the sheet is removed from the formingbelt, the resulting raised regions will naturally expand, therebyincreasing the raised area.

The overall preferred process can be as follows. A layer of nonwovenfiber material is provided and is positioned on a forming belt having adesired pattern to produce a cleaning sheet having macroscopicthree-dimensionality. The layer of fibers are then entangled in ahydroentanging unit thereby forming the cleaning sheet. The entanglesheet is then dried. The processes herein can optionally comprise a stepwherein the entangled webs are subject to heating, resulting inshrinkage of the substrate in the CD direction and increasing thecaliper of the cleaning sheet.

A more preferred process would be as follows. A first fibrous web (orlayer), a second reinforcing fibrous web (or layer), and a third fibrousweb (or layer) are provided. The first layer is positioned adjacent anupper surface of the reinforcing layer, in face to face relationshipwith the reinforcing layer. The third layer is positioned adjacent alower surface of the reinforcing layer, in face to face relationshipwith the reinforcing layer. The three layers are then placed on aforming belt having a desired pattern. The first layer and the thirdlayer are then entangled in a hydroentanging unit with the reinforcinglayer such that portions of the filaments extending between filamentintersections remain unbonded to the first layer, and such that portionsof the filaments extending between filament intersections remainunbonded to the third layer. The entangled sheet is then dried.

The step of intermittently bonding the reinforcing layer to the firstlayer and the third layer can comprise the step of heated pressing ofthe first layer, the reinforcing layer, and third layer at a relativelylow pressure for a relatively short time period to avoid relativelycontinuous bonding of the reinforcing layer to the first and thirdlayers.

III. Cleaning Implements

In another aspect, the present invention relates to a cleaning implementcomprising the cleaning sheets discussed herein. In this regard, thecleaning implement comprises a handle, a mop head, and a cleaning sheetof the present invention, wherein the cleaning sheet is removablyattachable to the mop head of the cleaning implement.

The handle of the cleaning implement comprises any elongated, durablematerial that will provide ergonomically practical cleaning. The lengthof the handle will be dictated by the end-use of the implement.

To facilitate ease of use, the mop head can be pivotably attached to thehandle using known joint assemblies. Any suitable means for attachingthe cleaning sheet to the support head can be utilized, so long as thecleaning sheet remains affixed during the cleaning process. Examples ofsuitable fastening means include clamps, hooks & loops (e.g., VELCRO®),and the like. In a preferred embodiment, the mop head will comprise“grippers” on its upper surface to keep the sheet mechanically attachedto the mop head during the rigors of cleaning. The grippers will alsoreadily release the sheet for convenient removal and disposable.Preferred grippers are described in co-pending U.S. application Ser. No.09/374,714 filed Aug. 13, 1999 by Kingry et al., which is incorporatedherein by reference.

To further improve glide characteristics and cleaning performance when apresent cleaning sheet is attached to a cleaning implement, the mop headof the cleaning implement can have curved profile on the bottom surfaceof the mop head. Suitable mop heads have curved bottom surfaces aredescribed in co-pending U.S. application Ser. No. 09/821,953 filed Mar.30, 2001 by Kacher et al., which is incorporated herein by reference.

Suitable cleaning implements are shown in U.S. Design Pat. Nos.D-409,343; and D-423,742; which are incorporated herein by reference.

IV. Methods of Use

The present invention further comprises methods of removing particulatematter from a surface comprising the step of contacting the surface witha cleaning sheet of the present invention. The cleaning sheets of thepresent invention are designed to be compatible with all hard surfacesubstrates, including wood, vinyl, linoleum, no wax floors, ceramic,FORMICA®, porcelain, and the like. They have also been found to beeffective on surfaces like walls, ceilings, upholstery, drapes, rugs,clothing, etc., where dusting sheets have not normally been used.

As a result of the ability of the cleaning sheets to reduce, oreliminate, by various means, including contacting and holding, dust,lint and other airborne matter from surfaces, as well as from the air,the sheets will provide greater reduction in the levels of suchmaterials on surfaces and in the atmosphere, relative to other productsand practices for similar cleaning purposes. This ability is especiallyapparent in sheets containing additive materials as described herein.Therefore it is important to provide this information on the package, orin association with the package, so as to encourage the use of thesheets, especially on the non-traditionally dusted surfaces like walls,ceilings, upholstery, drapes, rugs, clothing, etc.

The cleaning sheets herein are also useful for removing residue fromglass surfaces, such as fingerprints and other oily residues.

Consumers with allergies especially benefit from the use of the sheetsherein, especially the preferred structures, since allergens aretypically in dust form and it is especially desirable to reduce thelevel of small particles that are respirable. For this benefit, it isimportant to use the sheets on a regular basis, and not just when thesoil becomes visually apparent.

The invention also comprises articles of manufacture comprising thecleaning sheets of the present invention, the cleaning sheets beingcontained in a package in association with instructions for achievingone or more of the following benefits:

-   -   captures particulate soils on contact while minimizing dispersal        of said soils in the air as compared to normal dusting        techniques;    -   removes more particulate soil than normal dusting techniques;    -   removes invisible particulate matter;    -   does not require the application of an additional product;    -   uses electrostatic charge to pick up very fine particulate soil;    -   has a macroscopically three-dimensional structure to pick up        relatively large particles;    -   provides surface safety;    -   lowers the level of particulate material in the air;    -   reduces the level of particulate soil on a surface;    -   captures particulate soil on contact while minimizing dispersal        of said soil in the air as compared to normal dusting techniques        to minimize inhalation of said particulate soil and/or        redeposition of said particulate soil;    -   removes more particulate soil than normal dusting techniques so        that your surfaces are cleaner;    -   does not require the application of an additional product so        that the process is simplified.    -   requires less effort as compared to normal dusting techniques        since the particulate soil is more completely removed the first        time;    -   the process collects more particulate soil as compared to normal        dusting techniques so that it can be removed from the house or        other area;    -   results in a reduction of airborne allergens; or    -   results in a reduction of airborne pathogens.

These are packages containing cleaning sheets of the present invention,the packages being in association with information that will inform theconsumer, by words and/or by pictures, that use of the sheets willprovide the cleaning benefits. In a highly desirable variation, thepackage bears the information that informs the consumer that the use ofthe cleaning sheet provides reduced levels of dust and other airbornematter in the atmosphere. It is very important that the consumer beadvised of the potential to use the sheets on non-traditional surfaces,including fabrics, pets, etc., to ensure that the full benefits of thesheets is realized. Accordingly, the use of packages in association withinformation that will inform the consumer, by words and/or by pictures,that use of the compositions will provide benefits such as improvedcleaning, reduction of particulate soil in the air, etc. as discussedherein, is important. The information can include, e.g., advertising inall of the usual media, as well as statements and icons on the package,or the sheet itself, to inform the consumer.

EXAMPLES

The following Examples I-V are non-limiting examples of the cleaningsheets of the present invention.

Each example includes a substrate comprising a first fibrous web, asecond fibrous web, and a third reinforcing fibrous web, wherein thefirst and second fibrous webs are the same material. The first, second,and third fibrous webs are placed on top of a forming belt, with thethird reinforcing fibrous web being positioned in between the firstfibrous web and the second fibrous web. The forming belt comprises asolid pattern having a thickness of 0.43 mm, in a rounded parallelogramshape having a short diameter length of 4.66 mm a long diagonal lengthof 7.88 mm. The webs are then hydroentangled and dried. The waterentangling process causes the fibers of the first and second fibrouswebs to become intertangled and to also become intertangled with thefibers of the reinforcing fibrous web. The resulting substrate is thendried. The substrate is then optionally surface coated (by, e.g.,printing, spraying, etc.) with 5%, by weight, of a 3:7 mixture ofmineral oil and paraffin wax.

The total aggregate basis weight, CD elongation, and caliper arereported for each cleaning sheet example.

Example I

First/Second Fibrous Web: Carded fibrous web having a basis weight of 26g/m² and comprising staple polyester fibers having a denier of 1.5 ThirdReinforcing Thermal bonded fibrous web Fibrous Web: having a basisweight of 15 g/m² and comprising polypropylene fibers having a denier of2.2 Total Aggregate Basis 67 g/m² Weight: CD Elongation: 79% Caliper:1.41 mm

Example II

First/Second Fibrous Web: Carded fibrous web having a basis weight of 28g/m² and comprising 70% polyester fibers having a denier of 1.5, 15%polypropylene fibers having a denier of 2.2, and 15% of polypropylenefibers having a denier of 6.7, by weight of the web Third ReinforcingThermal bonded fibrous web having a Fibrous Web: basis weight of 15 g/m²and comprising polypropylene fibers having a denier of 6.7 TotalAggregate Basis 71 g/m² Weight: CD Elongation: 102% Caliper: 1.15 mm

Example III

First/Second Fibrous Web: Carded fibrous web having a basis weight of20.5 g/m² and comprising staple polyester fibers having a denier of 1.5Third Reinforcing Thermal bonded fibrous web having Fibrous Web: a basisweight of 23 g/m² and comprising polypropylene fibers having a denier of6.7 Total Aggregate Basis 64.2 g/m² Weight: CD Elongation: 71% Caliper:1.06 mm

Example IV

First/Second Fibrous Web: Carded fibrous web having a basis weight of26.7 g/m² and comprising staple polyester fibers having a denier of 1.5Third Reinforcing Spunbonded fibrous web having a basis Fibrous Web:weight of 16 g/m² and comprising polyester fibers having a denier of 6Total Aggregate Basis 69.4 g/m² Weight: CD Elongation: 11.9% Caliper:1.41 mm

Example V

First/Second Fibrous Web: Carded fibrous web having a basis weight of25.15 g/m² and comprising staple polyester fibers having a denier of 1.5Third Reinforcing Spunbonded fibrous web having a Fibrous Web: basisweight of 15 g/m² and comprising polyester fibers having a denier of 2.2Total Aggregate Basis 65.3 g/m² Weight: CD Elongation: 13.5% Caliper:1.28 mm

1. A cleaning sheet for removing particulate matter from a surface, saidcleaning sheet comprising a substrate comprising a first fibrous webcomprising carded staple fibers and a reinforcing fibrous web comprisingfibers selected from the group consisting of thermal bonded fibers,meltblown fibers, hydroentangled fibers, and spunbonded fibers; whereinsaid first fibrous web is hydroentangled with said reinforcing fibrousweb to form said substrate; and wherein said cleaning sheet has a CDelongation of less than about 100% at a load of 500 grams.
 2. Thecleaning sheet of claim 1 wherein said cleaning sheet has a CDelongation of less than about 70% at a load of 500 grams.
 3. Thecleaning sheet of claim 1 wherein said cleaning sheet has a CDelongation of from about 10% to about 100% at a load of 500 grams. 4.The cleaning sheet of claim 1 wherein said carded staple fibers arepolyester fibers and said reinforcing fibrous web comprises spunbondedfibers.
 5. The cleaning sheet of claim 4 wherein said spunbonded fibersare selected from the group consisting of polyester fibers,polypropylene fibers, polyethylene fibers, nylon fibers, rayon fibers,and mixtures thereof.
 6. The cleaning sheet of claim 5 wherein saidspunbonded fibers are polypropylene fibers.
 7. The cleaning sheet ofclaim 1 wherein said reinforcing fibrous web comprises thermal bondedfibers.
 8. The cleaning sheet of claim 7 wherein said thermal bondedfibers are selected from the group consisting of polyester fibers,polypropylene fibers, polyethylene fibers, nylon fibers, rayon fibers,and mixtures thereof.
 9. The cleaning sheet of claim 8 wherein saidthermal bonded fibers are polypropylene fibers.
 10. The cleaning sheetof claim 1 wherein said cleaning sheet has a total aggregate basisweight of from about 20 to about 200 g/m2.
 11. The cleaning sheet ofclaim 10 wherein said total aggregate basis weight is from about 40 toabout 100 g/m2.
 12. The cleaning sheet of claim 11 wherein said totalaggregate basis weight is from about 45 to about 80 g/m2.
 13. Thecleaning sheet of claim 10 wherein said reinforcing fibrous web has abasis weight of from about 5% to about 70% of said total aggregate basisweight.
 14. The cleaning sheet of claim 13 wherein said reinforcingfibrous web has a basis weight of from about 10% to about 50% of saidtotal aggregate basis weight.
 15. The cleaning sheet of claim 14 whereinsaid reinforcing fibrous web has a basis weight of from about 15% toabout 30% of said total aggregate basis weight.
 16. The cleaning sheetof claim 1 wherein said reinforcing fibrous web comprises fibers havinga denier of from about 0.5 to about
 12. 17. The cleaning sheet of claim16 wherein said reinforcing fibrous web comprises fibers having a denierof from about 1 to about
 6. 18. The cleaning sheet of claim 17 whereinsaid reinforcing fibrous web comprises fibers having a denier of fromabout 2 to about
 4. 19. The cleaning sheet of claim 1 wherein said firstfibrous web comprises first fibers having a denier of from about 0.5 toabout 12 and said reinforcing fibrous web comprises second fibers havinga denier of from about 0.5 to about 12; wherein the denier of saidsecond fibers is at least 0.5 greater than the denier of said fibers ofsaid first fibers.
 20. The cleaning sheet of claim 19 wherein saidcleaning sheet has a caliper of from about 0.3 to about 3 mm.
 21. Thecleaning sheet of claim 1 wherein said cleaning sheet is free of a scrimmaterial.
 22. The cleaning sheet of claim 1 wherein said cleaning sheetfurther comprises an additive material affixed to said substrate. 23.The cleaning sheet of claim 22 wherein said additive material isselected from the group consisting of wax, oil, and mixtures thereof.24. A cleaning implement for removing particulate matter from a surface,said cleaning implement comprising: (a) a handle; (b) a mop head connectto said handle via a joint; and (c) a cleaning sheet according to claim1, wherein said cleaning sheet is removably attached to said mop head.25. A cleaning implement for removing particulate matter from a surface,said cleaning implement comprising: (a) a handle; (b) a mop head connectto said handle via a joint; and (c) a cleaning sheet according to claim21, wherein said cleaning sheet is removably attached to said mop head.26. A method of removing particulate matter from a surface, said methodcomprising the step of contacting said surface with a cleaning sheetaccording to claim
 1. 27. A method of removing particulate matter from asurface, said method comprising the step of contacting said surface witha cleaning sheet according to claim 21.